Yes, CRT monitors lose "quality" over the years, especially if you have the brightness/contrast turned to the max. The phosphors that the electron guns strike dim over time, though high end monitors are less susceptible to this. Keep in mind that the backlight on LCD monitors dim over time as well, though newer backlights last much longer than older ones.

The solution is run at the proper brightness level for your ambient lighting. No point in putting out extra power when you don't need to.

The color guns also drift and require recalibration every once in a while.